Nowadays the use of laundry treatment appliances, such as laundry washing machines, i.e. laundry washing machines which wash and rinse laundry, or laundry washing and drying machines, i.e. laundry washing machines which can also dry laundry, is widespread. In this respect, in the present description, where not stated differently, the term “laundry washing machine” can be referred to a laundry washing machine, or a laundry washing and drying machines.
Laundry washing machines generally comprise an external casing provided with a washing tub which comprises a rotatable perforated drum where the laundry is placed, an electric motor which rotates the drum in the washing tub, a water-detergent supplying system which supplies fresh water and/or cleaning agents, i.e. detergent, into the washing tub/drum, and a water draining system which discharges/drains wash water/detergent from the washing tub.
A typical laundry washing course performed by laundry washing machines comprises various sequential laundry treating phases such as a main laundry wash phase, and a prefixed number of laundry rinse phases.
More specifically, during the main wash phase, the water-detergent supplying system adds fresh water and detergent into the washing tub until a prefixed water level is reached such that a cleaning solution is formed in the tub. Moreover, during the main wash phase, electrical heating means, i.e. an electrical resistor typically arranged in the bottom of the washing tub, are switched on to heat the loaded water in order to cause the washing temperature of the loaded water to reach a predetermined washing temperature based on the selected laundry washing course. To raise the temperature of the loaded water during the main laundry wash phase, it is therefore necessary to supply a high electric power to the electrical resistor that however heavily affects the whole electricity consumption of the laundry washing machine. For example, in the current laundry washing machine, to wash 4.5 kg of laundry it is required an electric power of 1.0 Kw to heat 16 liters of the washing water in order to increase the water temperature from 20 C to 60° C.
Recently, to prevent global warming, it is required to perform energy saving in the operation of electric machine/devices. In this respect, it is necessary to reduce the electricity consumption of the laundry washing machine and, in particular, decreasing the amount of electricity consumption of the electrical heating means needed for heating the washing water during the main laundry wash phase.
The Applicant has conducted an in-depth study with the objective of identifying a solution which specifically performs an energy saving during the main wash phase, without however affecting the laundry washing performances.
It is thus the object of the present invention to provide a solution which allows achieving the objective indicated above.